The introduction of metagenomics into an undergraduate biochemistry laboratory course yielded a predicted reductase that decreases triclosan susceptibility in Escherichia coli

Traditional undergraduate science classes often include a laboratory component aimed at enabling the students to experience the classroom topics firsthand. Typically, these experiments are chosen because they have known outcomes that will clearly demonstrate particular aspects of scientific theory. While this approach has its benefits in skill development and concept reinforcement, the lack of novelty inherent in repeating experiments that have been repeated for many years does not accurately convey the feeling of true scientific discovery to the students. In this work, we have designed and implemented a series of experiments into an undergraduate biochemistry curriculum that incorporates the opportunity for scientific discovery, while simultaneously creating an environment for learning routine laboratory techniques. Through this set of experiments, students enrolled in the course were successful in identifying and beginning to characterize an unknown bacterial gene that confers increased tolerance to triclosan on its host.     

An introductory student-centred class to teach concepts related to spectrophotometry in a biochemistry practical laboratory course

Students were asked to investigate ways of determining the concentration of a coloured compound by various methods, including spectrophotometry. This was put to them as a problem-solving challenge rather than being presented as a cook-book type of protocol. Their responses to this method of learning (active or passive) were evaluated. Some students did well by this method and developed their concepts in a constructive way while others would have preferred to have been given a protocol and told exactly what to do.     

Xylose as a nectar sugar: from biochemistry to ecology

Studies of nectar sugar composition in the Proteaceae, an ancient southern hemisphere plant family, have demonstrated that xylose comprises up to 39% of nectar sugar in two genera, Protea and Faurea, and may therefore represent a substantial fraction of the energy available to pollinators of these plants. Although insect and bird pollinators of Protea species are averse to xylose, mice (Aethomys namaquensis) will drink pure xylose, which is metabolized either by gut bacteria or by the mouse tissues. In the form of xylan polymers, the pentose sugar -xylose is a structural component of plant cell walls, and there is considerable biotechnological interest in xylose fermentation. Bacteria and yeasts convert -xylose to -xylulose and thence via the pentose phosphate pathway to fructose-6-phosphate, which is either oxidized or fermented to ethanol. Gut symbionts of rodent pollinators may be analogous to ruminal xylose-metabolizing bacteria. The presence of xylose in Protea and Faurea nectar remains puzzling in view of pollinator aversions: even for rodent pollinators, it is the least preferred nectar sugar. In the generalized pollination systems of the Proteaceae, a coevolutionary explanation for nectar xylose as an attractant for mammalian pollinators is probably less likely than one involving plant physiology, with xylose in phloem sap being secreted passively into the nectar.     

Problem-oriented small-group discussion in the teaching of biochemistry laboratory practicals

An experiment on the use of problem-based exercises in an Indian Medical School is described. Problem-based classes were supplemented with laboratory classes and feedback from both students and tutors was analyzed.     

Computerised data acquisition and analysis in the biochemistry teaching laboratory

We have successfully implemented a simple computerised data acquisition system which has been used extensively in our biochemistry teaching laboratory classes. Our experience suggests that it is important to consider carefully what the computers are required to do in the laboratory well before their introduction. Finally, we believe that it is desirable to keep the system simple and sufficiently versatile that it can be adapted to several different uses without too much difficulty.     

Greenbeards in yeast: an undergraduate laboratory exercise to teach the genetics of cooperation

Recent years have seen a dramatic increase in our understanding of the social behaviour of microbes. Here, we take advantage of these developments to present an undergraduate laboratory exercise that uses the cooperative flocculating behaviour of yeast (Saccharomyces sp.) to introduce the concept of inclusive fitness and teach the genetics of cooperation. Students generate their own data using co-cultures of various yeast strains and perform statistical analyses to test whether kin selection or greenbeard effects determine the cooperative flocculating behaviour. The lab has run successfully for two consecutive years in a second year course with some 1, 200 students per year at the University of Toronto, Canada. We discuss the benefits of using microbes to teach social evolution, describe the set-up and learning outcomes of the laboratory exercise, and then outline possible extension and variants of the lab. In addition to providing students with the opportunity to use a model organism to study social behaviour, students are also taught common laboratory skills, such as replica plating and sterile techniques. Ultimately, while the genetics of cooperation has traditionally been taught through computer simulations and evolutionary games, this exercise demonstrates a way to experimentally introduce the topic.